We plan to study the regulation of enzymes requiring vitamin B6 and folic acid, involved in the metabolism of serine and threonine. Special emphasis will be placed on the relationship of these reactions to homocystinuria neogenesis of labile methyl groups, metabolic pathways and control mechanisms in mammalian systems. The enzymes: serine-threorine dehydratase, serine hydroxymethylase threonine aldolase, and methylene tetrahydrofolate reductase. BIBLIOGRAPHIC REFERENCES: An Investigation of The Role of The Copper in Galactose Oxidase, L. Cleveland, P. Coon, R. Coffman, and L. Davis, Biochemistry, 14, 1108 (1975). Deamination of The Microbial Toxin Trans L-2-Amino-4-methoxy-3-butenoic Acid and Its Parent Vinylglycine by Sheep Liver Serine-Threonine Dehydratase, G. Kapke and L. Davis, Biochem. and Biophys, Res. Commun., 65, 765 (1975).